J/ApJS/282/15 4-8GHz TMRT obs. of WISE point sources (Liu+, 2026)
A 6 cm formaldehyde line survey toward WISE point sources.
Liu J.-T., Chen Xi, Ouyang X.-J., Zhang Y.-K., Song S.-M., Zhao Z., Li B.,
Xia Bo, Shen Z.-Q.
<Astrophys. J. Suppl. Ser., 282, 15 (2026)>
=2026ApJS..282...15L 2026ApJS..282...15L
ADC_Keywords: Infrared sources; Radio lines; Interstellar medium; Masers
Keywords: Interstellar medium ; Star forming regions ; Young stellar objects ;
Interstellar line absorption ; Interstellar masers
Abstract:
We conducted a 6cm formaldehyde (H2CO) line survey across the northern
sky, targeting 3149 high-mass star-forming region candidates selected
from the all-sky Wide-field Infrared Survey Explorer (WISE)
point-source catalog using the Shanghai TianMa 65m Radio Telescope.
This survey detected H2CO absorption lines at 1156 positions and four
known maser sources, achieving a detection rate of 36.7%. Among these,
14 candidates exhibited hyperfine structure splitting, all located at
high Galactic latitudes (b>3°). The Galactic spatial distribution
of H2CO absorption line detections yields a scale height of ∼71.8pc.
Compared to the WISE infrared colors and magnitudes of 6.7GHz CH3OH
masers and hydrogen radio-recombination lines (HRRLs), the
distribution of H2CO absorption lines closely resembles that of HRRLs,
albeit with higher [W4] magnitudes. The detection of these three lines
in the same observational sample enables the classification of H2CO
absorption lines into four groups representing distinct evolutionary
stages. Variations in H2CO detection proportion, line width, and
intensity across these groups probably reflect the influence of star
formation feedback on the circumstellar medium during protostellar
evolution. Observational updates over six years (2015-2021) of the 6cm
H2CO maser in NGC 7538 IRS1 demonstrate that the flux density diverged
from the prediction of the rotating ellipsoidal model, highlighting
the need for further data to elucidate the maser variability
mechanism.
Description:
The observation sample was initially designed to search for 6.7GHz
methanol masers, while the 4.8GHz H2CO line also falls within the
bandwidth of the C-band receiver of the Shanghai Tianma 65m Radio
Telescope (TMRT), enabling the simultaneous observation of multiple
spectral lines. The primarily observed spectral line information is
provided in Table 1 of Chen+ (2020, J/ApJS/248/3). The detailed
information on sample selection and related parameters is provided in
Section 2 of Yang+ (2017, J/ApJ/846/160).
We performed a crossmatch between the Methanol Multibeam (MMB) 6.7GHz
CH3OH maser catalog (which encompasses 684 sources within
186°<l<20° and |b|<2°; Green+ 2009MNRAS.392..783G 2009MNRAS.392..783G,
2010MNRAS.409..913G 2010MNRAS.409..913G, 2012MNRAS.420.3108G 2012MNRAS.420.3108G, 2017MNRAS.469.1383G 2017MNRAS.469.1383G;
Caswell+ , 2011, VIII/96 & Breen+ 2015MNRAS.450.4109B 2015MNRAS.450.4109B, 2018MNRAS.474.3898B 2018MNRAS.474.3898B)
and the all-sky Wide-field Infrared Survey Explorer (WISE) infrared
photometry catalog (Wright+ 2010, see II/311 & II/328) with a matching
radius of 7". See Section 2.1.
The survey was conducted with the TMRT between 2015 September and
2018 January. A cryogenically cooled C-band receiver, spanning the
frequency range of 4-8GHz.
A set of 16 spectral windows, each with a bandwidth of 23.4375MHz and
comprising 16,384 channels, was used in the observations, yielding a
channel spacing of 1.431kHz, corresponding to a velocity resolution of
0.089km/s for the 4.8GHz H2CO transition. At this frequency, the beam
size (half-power beamwidth) is 3.35'.
See Section 2.2.
In the observations, 4.8GHz H2CO absorptions were detected in
1156 out of 3149 targeted positions, comprising 1555 Gaussian
components.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 109 261 Spectral line properties of the 4.8GHz H2CO
absorption and maser toward four identified maser
sources
tablea1.dat 135 1555 Characteristics of 1555 4.8GHz H2CO absorption
components detected toward 1156 sources
tablea2.dat 54 1989 Characteristics of 1989 sources with non-detected
4.8GHz H2CO absorption
--------------------------------------------------------------------------------
See also:
VIII/96 : 6-GHz methanol multibeam maser catalogue (Caswell+, 2010-12)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/A+A/275/67 : Velocity Field of the outer Galaxy (Brand+ 1993)
J/MNRAS/301/640 : Ultracompact H II regions studies. II. (Walsh+, 1998)
J/ApJS/138/63 : H2CO and Hα observations of UC HII (Araya+, 2002)
J/ApJ/582/756 : Velocities of HII regions (Kolpak+, 2003)
J/A+A/403/1095 : 6.7GHz methanol masers of low-mass YSO (Minier+, 2003)
J/ApJ/587/714 : H2CO and Hα observations of UC HII (Watson+, 2003)
J/ApJS/154/553 : Inner galaxy massive star formation regions (Sewilo+, 2004)
J/MNRAS/366/1096 : Kinematic distance ambiguity (Busfield+, 2006)
J/ApJ/690/706 : Distances of Galactic HII regions (Anderson+, 2009)
J/ApJ/717/L133 : Formaldehyde maser flares in IRAS 18566+0408 (Araya+, 2010)
J/ApJS/194/32 : HII Region Discovery Survey (HRDS). II. (Anderson+, 2011)
J/ApJ/770/39 : BGPS. VIII. MIR kinematic dist. (Ellsworth-Bowers+, 2013)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/MNRAS/443/1555 : ATLASGAL massive star forming clumps (Urquhart+, 2014)
J/A+A/600/A16 : Six LMC star forming region spectra (Tang+, 2017)
J/A+A/598/A30 : Massive star forming molecular clumps Tkin (Tang+, 2017)
J/ApJ/846/160 : 6.7GHz Class II methanol maser survey (Yang+, 2017)
J/A+A/609/A16 : OMC 1 reduced H2CO(3-2) datacubes (Tang+, 2018)
J/A+A/611/A6 : ATLASGAL massive clumps H2CO data (Tang+, 2018)
J/ApJS/244/35 : VLA observations of the Central Molecular Zone (Lu+, 2019)
J/ApJS/245/12 : 6.7GHz methanol masers & RRLs in MSX regions (Ouyang+, 2019)
J/ApJ/885/131 : High-mass SFR plx & proper motion with VLBI (Reid+, 2019)
J/ApJS/241/18 : A 6.7GHz methanol maser survey. II. |b|<2° (Yang+, 2019)
J/ApJS/248/3 : A 4-6GHz RRL survey in the Milky Way (Chen+, 2020)
J/A+A/646/A170 : Serpens filament 13CO, C18O & C17O datacubes (Gong+, 2021)
J/ApJ/910/131 : Molecular gas distribution from MWISP CO survey (Su+, 2021)
J/A+A/655/A12 : LMC N113 and N159W ALMA para-H2CO datacubes (Tang+, 2021)
J/ApJS/262/42 : VLBA obs. of masers in the Scutum Spiral Arm (Li+, 2022)
J/A+A/689/A81 : GLOSTAR GPS. X. Galactic HII region catalog (Khan+, 2024)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Source name ("G23.01-0.41", "G32.74-0.07",
"IRAS18566+0408" or "NGC∼7538∼IRS1")
16- 28 A13 --- Comp Component, absorption or maser (1)
30- 31 I2 h RAh [18/23] Hour of Right Ascension, TMRT obs.
pointing center (J2000)
33- 34 I2 min RAm Minute of Right Ascension, TMRT obs.
pointing center (J2000)
36- 40 F5.2 s RAs Second of Right Ascension, TMRT obs.
pointing center (J2000)
42 A1 --- DE- Sign of the Declination, TMRT obs. pointing
center (J2000)
43- 44 I2 deg DEd Degree of Declination, TMRT obs. pointing
center (J2000)
46- 47 I2 arcmin DEm Arcminute of Declination, TMRT obs. pointing
center (J2000)
49- 52 F4.1 arcsec DEs Arcsecond of Declination, TMRT obs. pointing
center (J2000)
54- 63 A10 "Y/M/D" Epoch Observation epoch (UTC)
65- 67 I3 mJy rms [19/151] Observational rms noise level
69- 74 F6.2 km/s Vpeak [-60.2/85.3] LSR velocity at the peak value
(G1)
76- 79 F4.2 km/s e_Vpeak [0.01/1] Uncertainty in Vpeak (G1)
81- 84 F4.2 km/s FWHM [0.23/9.82] Full Width at Half Maximum (G1)
86- 89 F4.2 km/s e_FWHM [0.02/2.06] Uncertainty in FWHM (G1)
91- 94 I4 mJy Speak [-636/1698] peak flux density (G1)
96-100 I5 mJy.km/s Sint [-4116/1509] Integrated flux density (G1)
102-104 I3 mJy.km/s e_Sint [8/360] Uncertainty in Sint (G1)
106-109 I4 mJy Speak2 [115/1765]? Peak flux density, directly
extracted from the spectrum
--------------------------------------------------------------------------------
Note (1): Rows labeled "absorption" in this column correspond to
absorption components, which have negative Speak and Sint values,
while maser components have positive values. This difference is
illustrated in the spectral profiles shown in Figure 3.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- File File name of the spectrum PDF (1)
14- 28 A15 --- Name Source name
30- 31 I2 h RAh Hour of Right Ascension, TMRT obs. pointing
center (J2000)
33- 34 I2 min RAm Minute of Right Ascension, TMRT obs. pointing
center (J2000)
36- 40 F5.2 s RAs Second of Right Ascension, TMRT obs. pointing
center (J2000)
42 A1 --- DE- Sign of the Declination, TMRT obs. pointing
center (J2000)
43- 44 I2 deg DEd Degree of Declination, TMRT obs. pointing
center (J2000)
46- 47 I2 arcmin DEm Arcminute of Declination, TMRT obs. pointing
center (J2000)
49- 52 F4.1 arcsec DEs Arcsecond of Declination, TMRT obs. pointing
center (J2000)
54- 63 A10 "Y/M/D" Epoch Observation epoch (UTC)
65- 69 F5.3 K rms [0.01/0.4] Observational rms noise level
71- 77 F7.2 km/s Vpeak [-103.1/121.3] LSR velocity at the peak value
(G1)
79- 82 F4.2 km/s e_Vpeak [0.01/0.8] Uncertainty in Vpeak (G1)
84- 88 F5.2 km/s FWHM [0.23/31.4] Full Width at Half Maximum (G1)
90- 93 F4.2 km/s e_FWHM [0.01/2] Uncertainty in FWHM (G1)
95- 100 F6.3 K Tpeak [-7.52/-0.06] peak main beam temperature (G1)
102- 108 F7.3 K.km/s TmbdV [-39.31/-0.03] Integrated area (G1)
110- 114 F5.3 K.km/s e_TmbdV [0.01/1.2] Uncertainty in TmbdV (G1)
116- 119 F4.1 kpc dist-p [0.7/12.5]? Parallax distance (3)
121- 125 F5.2 kpc dist-b [0.16/19.8]? Bayesian distance with error
calculated using peak velocity (4)
127- 130 F4.2 kpc e_dist-b [0.01/7.3]? Uncertainty in dist-b
132 A1 --- 6.7GHz [Y ] Association with 6.7GHz CH3OH masers (G2)
134- 135 A2 --- RRLs Association with RRLs (G3)
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Note (1): As displayed (examples) in Figure A1.
Note (3): Parallax distance extracted from Reid+ 2019, J/ApJ/885/131;
Xu+ 2021ApJS..253....1X 2021ApJS..253....1X; Li+ 2022, J/ApJS/262/42
Note (4): Bayesian distance with error calculated using peak
velocity. The distances were derived from the Parallax-Based
Distance Calculator V2 (http://bessel.vlbi-astrometry.org/node/378)
with a default equal weighting (Pfar=0.5) on near and far distance
probability. The detailed description refers to section 3.1.3.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source name
17- 18 I2 h RAh Hour of Right Ascension, TMRT obs. pointing
center (J2000)
20- 21 I2 min RAm Minute of Right Ascension, TMRT obs. pointing
center (J2000)
23- 27 F5.2 s RAs Second of Right Ascension, TMRT obs. pointing
center (J2000)
29 A1 --- DE- Sign of the Declination, TMRT obs. pointing
center (J2000)
30- 31 I2 deg DEd Degree of Declination, TMRT obs. pointing
center (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination, TMRT obs. pointing
center (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of Declination, TMRT obs. pointing
center (J2000)
41- 45 F5.3 K rms [0.028/2.81] Observational rms noise level
47 A1 --- 6.7GHz [Y ] Association with 6.7GHz CH3OH masers (G2)
49- 54 A6 --- RRLs Association with RRLs (G3)
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Global Note:
Note (G1): Obtained from gaussian fitting.
Note (G2): Association with 6.7GHz CH3OH masers where 'Y' represents
'Yes', data from Yang+ (2017, J/ApJ/846/160 & 2019, J/ApJS/241/18).
Note (G3): association with RRLs from Chen+ (2020, J/ApJS/248/3) as follows:
H = H RRL
He = He RRL
C = C RRL
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Jul-2026